The Calgary woman charged in the death of her disabled adult daughter said demons in the wall were causing a horrible stench in her home, court heard Thursday.

Bryan Couture, the ex-husband of Patricia Couture and the father of their daughter Melissa, said he complained to his former spouse about the excrement-like smell in their former matrimonial residence.

"I knew at the time Pat was changing Melissa on the couch which was easier for Pat than taking her to the washroom," said Couture, who testified his daughter by that time had to wear adult diapers.

"I would come in and say 'Pat, you've got to open the doors' and then I would open the doors to try to get some of the odours out," he said.

"It was definitely a smell of poop — excrement."

Eventually she explained "it was demons living in the walls, that's what they smelled like," Couture testified.

"When it finally didn't go away, that was the answer."

Patricia Couture, 70, is charged with criminal negligence causing death in the April 26, 2016, demise of her severely disabled daughter, 38, who suffered from cerebral palsy.

Before Bryan Couture took the witness stand in the Crown's case, his lawyer, Ian McKay appeared before provincial court Judge John Bascom to say his client was evoking a section of the Canada Evidence Act that protects witnesses from giving incriminating evidence against themselves.

"Nothing that Mr. Couture says today can be used in any future prosecution against him," Bascom ordered after hearing McKay's submissions.

Couture then took the witness stand to explain how he watched as his daughter — whom he described as "a special gift" — slowly deteriorated before her death.

But Couture said he didn't appreciate the full gravity of his daughter's health until she died.

Before then he had asked the accused to take Melissa to the doctor, but she declined to do so.

At one point he recommended she be taken to emergency and his ex-wife said she'd think about it.

But when he raised the issue two weeks later the accused "didn't really have an answer," he told chief Crown prosecutor Sue Kendall.

"I knew what I was going to do, but Melissa passed away," he explained.

"I would've taken Melissa by force if Pat didn't agree."

"But Melissa died, how do you feel about that?" Kendall asked.

"I was shocked when she died. I feel terrible about it, especially what I read in the paper," he said.

"I can't believe what I read ... I believe it said there was exposed bone and I couldn't believe that."

In testimony on Thursday, medical examiner Bamidele Adeagbo said pressure sores on Melissa's were so severe they exposed bone.

Couture also said his former wife equated doctors with demons.

"She said no doctors ... she said naturopaths," he explained.

"I said why no doctors ... is that because of demons? And she said yes."

He testified he was concerned about her mental health for years.

"Just what some of her beliefs were and how she got into demonic things," he said.